FIG. 1 illustrates a related injection molded product, and what illustrated in FIG. 1a is that a predetermined pattern is formed as printing with ink (the present specification gives a pattern formed with letters as an example) on the injection molded product. However, this case has some disadvantages in that much of costs and time are needed due to the addition of the process for manufacturing cabinets and etc used for various image display device, since the printing process has to be added after the injection molding.
Another injection molded product is illustrated in FIG. 1b, and an intaglio pattern “Canon” is formed as illustrated. The injection molded product on which an embossed pattern or an intaglio pattern are formed does not need a separate printing process as different from the injection molded product illustrated in FIG. 1a. However, the intaglio pattern or embossed pattern is not beautiful and is regarded as weary, since it has been used for a long time, and because of this, the demands for injection molded products on which new patterns are formed has been raised in the related industry.
Starting the above-mentioned demands, the subject about forming patterns with any other method on the same plane excepting printing was raised, and the method forming patterns as etched was examined. FIG. 2 illustrates an injection molded material which is injection molded by a mold that the surface is treated as etched.
FIG. 2a is a photograph taken as the real size, FIG. 2b is a photograph that the a portion r1 of FIG. 2a is taken as magnified 600 times, and FIG. 2c is a result of measuring prominence as cutting off along the line c1 in FIG. 2a (progressing speed of a measuring instrument is 0.3 mm/s, and the measuring cut off is 0.8 mm). For further reference, the line marked a1 is the line corresponding to the average height of the prominence of represented part w1.
As a result of measuring the part w1 which is wide enough to secure the representing quality on the surface s1, the arithmetic average roughness of the prominence is about 9.154 μm, and the average thickness is about 200 μm.
However, the straight quality of the boundary is reduced due to the thickness of the prominence when the boundary of pattern is formed on the surface of the injection molded product due to the surface on which thick prominence as above is formed and the even surface (surface almost reflecting objects) that is in the limelight recently, therefore, the external appearance cannot be beautiful.